Reading narrow data tracks with multiple wide readers

ABSTRACT

Technologies are described herein for utilizing multiple, wide readers to read narrow data tracks on a magnetic recording media in a storage device. A system for reading a data track on a magnetic recording media comprises a plurality of reader elements, the width of each reader element being an integer greater than 1 multiple of a width of the data tracks on the recording media. The system further comprises a multi-reader decoder module operably connected to the plurality of reader elements. Each of the reader elements is configured to read a magnetic signal from the magnetic recording media. The multi-reader decoder module is configured to receive a read signal from each of the reader elements, and decode the data on the data track based on the read signals from the reader elements.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/446,047, filed Jul. 29, 2014, and entitled “READING NARROW DATATRACKS WITH MULTIPLE WIDE READERS,” the entirety of which is herebyincorporated herein by this reference.

BRIEF SUMMARY

The present disclosure relates to technologies for utilizing multiple,wide readers to read narrow data tracks on a magnetic recording media,such as that in a hard-disk drive (“HDD”) device. According to someembodiments, a system for reading a data track on a magnetic recordingmedium comprises a plurality of reader elements and a multi-readerdecoder module operably connected to the plurality of reader elements.Each of the reader elements is configured to read a magnetic signal fromthe magnetic recording media. Each reader element may be wider than awidth of the data track on the recording media. The multi-reader decodermodule is configured to receive a read signal from each of the readerelements, and decode the data on the data track based on the readsignals from the reader elements.

According to further embodiments, a method for reading a target datatrack on a recording media comprises receiving a read signal from eachof a plurality of reader elements, the read signal indicating asummation of data on the target data track and one or more adjacenttracks. At least one of the plurality of reader elements is wider thanthe target data track on the recording media. The data on the targettrack is then determined based on the read signals from the plurality ofreader elements.

According to further embodiments, a read/write channel of an HDD devicecomprises a plurality of multi-level detectors and a mapper. Each of themulti-level detectors is configured to detect multiple levels in readsignals from a plurality of reader elements and generate an associatedmulti-level value. At least one of the plurality of reader elements iswider than data tracks written to a recording media of the HDD device.The mapper is configured to convert the multi-level values from theplurality of multilevel detectors to bit data stored on a target datatrack on the recording media.

These and other features and aspects of the various embodiments willbecome apparent upon reading the following Detailed Description andreviewing the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following Detailed Description, references are made to theaccompanying drawings that form a part hereof, and that show, by way ofillustration, specific embodiments or examples. The drawings herein arenot drawn to scale. Like numerals represent like elements throughout theseveral figures.

FIG. 1 is a block diagram showing a system for reading a data track on amagnetic media utilizing multiple, wide readers, according toembodiments described herein.

FIG. 2 is a block diagram showing an illustrative environment forutilizing multiple, wide readers to read narrow data tracks on amagnetic recording media in a storage device, according to embodimentsdescribed herein.

FIGS. 3-6 are block diagrams showing aspects of systems for reading adata track on a magnetic media utilizing multiple, wide readers,according to embodiments described herein.

FIG. 7 is a block diagram showing further aspects of systems for readingdata from a data track utilizing multiple wide readers in multiplepasses, according to embodiments described herein.

FIG. 8 is a flow diagram showing one routine for reading data from adata track utilizing multiple, wide readers, according to embodimentsdescribed herein.

FIG. 9 is a flow diagram showing another routine for reading data from adata track utilizing multiple, wide readers, according to embodimentsdescribed herein.

DETAILED DESCRIPTION

The following detailed description is directed to technologies forutilizing multiple, wide readers to read narrow data tracks on amagnetic recording media. A typical storage device may include ahard-disk drive (“HDD”) device. The HDD device may contain a number ofmagnetic storage disks that include a number of concentric data trackscontaining the data stored on the device. As the storage capacity of HDDdevices increase, the areal density capability (“ADC”) of the storagedisks may also increase. The ADC of a storage disk has two maincomponents: the number of bits of data that can be squeezed on the disksin along-track direction, measured in bits-per-inch (“BPI”), and thenumber of data tracks squeezed into a cross-track direction, measured intracks-per-inch (“TPI”). The ADC may be expressed as the multiplicationof BPI and TPI

Perpendicular magnetic recording (“PMR”) technology used widely in HDDdevices is approaching its superparamagnetic limit at existing storagedensities, which restricts device manufactures from increasing ADC ofthe storage disks. In addition, alternative recording technologies tothe existing PMR technology favor higher TPI more than PMR technology.For example, Shingled Magnetic Recording (“SMR”) by design writesnarrower tracks. Heat-assisted magnetic recording (“HAMR”) light sourcesalso naturally favor high TPI designs, which mean narrower data tracks.Bit-pattern media (“BPM”) dots also prefer to be closer to each otherfor both along-track and cross-track directions.

Reader width scaling represents a major challenge to high TPI designs inthe recording media of HDD devices. The design of readers narrow enoughto fit into the narrow tracks so that they do not read interference fromadjacent tracks without losing their required reader signal-to-noiseratio (“SNR”) is difficult and readers meeting these requirements may beexpensive. According to the embodiments described herein, storage devicesystems, apparatus, and methods may be implemented to handle high TPImedia with multiple readers much wider than the data track width. Thesesystems may use existing reader designs instead of requiring a newdesign for a single, very narrow reader. In addition, thesemultiple-reader systems may be utilized with conventional writingtechniques. These systems may also be utilized with systems haveexisting media design, where the reader width is more comparable to thewritten track width, as will be described herein.

FIG. 1 provides an overview of an illustrative system 100 that utilizesmultiple, wide readers to read narrow data tracks on a magneticrecording media of a storage device, according to the embodimentsdescribed herein. The system 100 comprises multiple reader elements102A-102C (referred to herein generally as reader element 102). Thereader elements 102 may represent magneto-resistive (“MR”) readers on aread/write head of the storage device, for example. As may be seen inthe figure, each of the reader elements 102, in this embodiment is muchwider than the width of the data tracks 104A-104C (referred to hereingenerally as data track 104) written to the recording media 106. Areader that is significantly wider than the width of the data tracks 104written to the media, such as reader element 102A, makes conventionalrecording/reading methods difficult because the reader will read a lotof interference from adjacent tracks. Instead, the system of FIG. 1utilizes two reader elements 102A and 102B that are as wide as 2× thewritten track width. The system may optionally utilize a third reader102C that is 3× the written track width.

The system 100 further comprises a multi-reader decoder module 108. Themulti-reader decoder module 108 may comprise components and/or softwarein the controller of the storage device. As will be described in moredetail below, during a read operation of the storage device, themulti-reader decoder module 108 receives the read signals from themultiple reader elements 102 in order to detect multiple levels undereach reader. The multi-reader decoder module 108 may then utilize thedetected levels to decode the bits of data written to a target datatrack of the read operation, such as data track N 104B. In this fashion,by using multiple readers much wider than the written data tracks, thesystem can still resolve one narrow track. According to embodiments, thestorage device may employ existing reader design to read the narrow datatracks 104 of high TPI media, thus reducing the design costs associatedwith producing a narrow reading element. In addition, conventional writeprocesses may be utilized in the storage device, further reducing thecosts of implementation.

FIG. 2 and the following description are intended to provide a generaldescription of a suitable environment in which the embodiments describedherein may be implemented. In particular, FIG. 2 shows an illustrativestorage device 200, such as an HDD apparatus, along with hardware,software and components for utilizing multiple, wide readers to readnarrow data tracks on a magnetic recording media, according to theembodiments provided herein. The storage device 200 may includerecording media comprising at least one platter or disk 202. The disk(s)202 may include a magnetic recording surface divided or “formatted” intoa number of individual data tracks, such as data track 104. The datatracks 104 may represent substantially concentric circular areas on thesurface of the disk 202.

The storage device 200 further includes at least one read/write head 204located adjacent to the recording surface of each disk 202. Theread/write head 204 may read information from the disk 202 by sensing amagnetic field formed on portions of the surface of the disk, and maywrite information to the disk by magnetizing a portion of the surface ofthe disk. The read/write head 204 may be located at the distal end of anarm 206 that rotates in order to reposition the read/write head 204.According to embodiments, the read/write head 204 includes multiplereader elements, such as reader elements 102A-102C. The reader elements102 may comprise magneto-resistive (“MR”) readers, tunneling MR readers,or the like. It will be appreciated that the size, location, andrelative orientation of the reader elements 102 shown in FIG. 2 are forillustrative purposes only, and one of ordinary skill in the art willrecognize that other sizes, locations, and relative orientations arepossible and part of this disclosure. According to further embodiments,at least one reader element 102 of the read/write head is wider than thewidth of the data tracks 104 written to the surface of the disk(s) 202.The read/write head 204 may further include other components not shownin the figure or described herein, such as writer elements, headheaters, air bearings, and the like.

The storage device 200 may further comprise a controller 220 thatcontrols the operations of the storage device. The controller 220 mayinclude a processor 222. The processor 222 may implement an interface224 allowing the storage device 200 to communicate with a host device,other parts of storage device 200, or other components, such as a servercomputer, personal computer (“PC”), laptop, tablet, game console,set-top box or any other electronics device that can be communicativelycoupled to the storage device 200 to store and retrieve data from thestorage device. The processor 222 may process write commands from thehost device by formatting the associated data and transfer the formatteddata via a read/write channel 226 through the read/write head 204 and tothe surface of the disk 202. The processor 222 may further process readcommands from the host device by determining the location of the desireddata on the surface of the disk 202, moving the read/write head(s) 204over the determined location, reading the data from the surface of thedisk via the read/write channel 226, correcting any errors andformatting the data for transfer to the host device.

The read/write channel 226 may convert data between the digital signalsprocessed by the processor 222 and the analog signals conducted throughthe read/write head 204 for reading and writing data to the surface ofthe disk 202. The analog signals to and from the read/write head 204 maybe further processed through a pre-amplifier circuit. The read/writechannel 226 may further provide servo data read from the disk 202 to anactuator to position the read/write head 204. The read/write head 204may be positioned to read or write data to a specific location on the onthe recording surface of the disk 202 by moving the read/write head 204radially across the data tracks 104 using the actuator while a motorrotates the disk to bring the target location under the read/write head.

According to embodiments, the controller 220 may further contain amulti-reader decoder module 108. The multi-reader decoder module 108receives the read signals from the multiple reader elements 102 anddecodes the bits of data written to the target data track 104 during aread operation. The multi-reader decoder module 108 may comprisehardware circuits in the read/write channel 226, processor-executableinstructions for execution in the processor 222 or any combination ofthese and other components in the controller 220. The multi-readerdecoder module 108 may implement the various sub components describedherein for utilizing multiple, wide readers to read narrow data trackson a magnetic recording media.

The controller 220 may further include a computer-readable storagemedium or “memory” 230 for storing processor-executable instructions,data structures and other information. The memory 230 may comprise anon-volatile memory, such as read-only memory (“ROM”) and/or FLASHmemory, and a random-access memory (“RAM”), such as dynamic randomaccess memory (“DRAM”) or synchronous dynamic random access memory(“SDRAM”). For example, the non-volatile memory and/or the RAM may storea firmware that comprises commands and data necessary for performing theoperations of the storage device 200. According to some embodiments, thememory 230 may store processor-executable instructions that, whenexecuted by the processor, perform the routines 800 and 900 forutilizing multiple, wide readers to read narrow data tracks on amagnetic recording media of the storage device 200, as described herein.

In addition to the memory 230, the environment may include othercomputer-readable media storing program modules, data structures, andother data described herein for utilizing multiple, wide readers to readnarrow data tracks on a magnetic recording media of the storage device200. It will be appreciated by those skilled in the art thatcomputer-readable media can be any available media that may be accessedby the controller 220 or other computing system for the non-transitorystorage of information. Computer-readable media includes volatile andnon-volatile, removable and non-removable recording media implemented inany method or technology, including, but not limited to, RAM, ROM,erasable programmable ROM (“EPROM”), electrically-erasable programmableROM (“EEPROM”), FLASH memory or other solid-state memory technology,compact disc ROM (“CD-ROM”), digital versatile disk (“DVD”), highdefinition DVD (“HD-DVD”), BLU-RAY or other optical storage, magneticcassettes, magnetic tape, magnetic disk storage or other magneticstorage devices and the like.

It will be appreciated that the structure and/or functionality of thestorage device 200 may be different than that illustrated in FIG. 2 anddescribed herein. For example, the processor 222, read/write channel226, memory 230 and other components and circuitry of the storage device200 may be integrated within a common integrated circuit package ordistributed among multiple integrated circuit packages. Similarly, theillustrated connection pathways are provided for purposes ofillustration and not of limitation, and some components and/orinterconnections may be omitted for purposes of clarity. It will befurther appreciated that the storage device 200 may not include all ofthe components shown in FIG. 2, may include other components that arenot explicitly shown in FIG. 2 or may utilize an architecture completelydifferent than that shown in FIG. 2.

FIG. 3 provides additional details of one system 300 for utilizingmultiple, wide readers to read narrow data tracks on a magneticrecording media of a storage device. As in the illustrative system shownin FIG. 1, the system 300 of FIG. 3 includes three reader elements: tworeader elements 102B and 102C that are as wide as 2× the width of thedata tracks 104A-104C written to the recording media, and a third reader102A that is 3× the track width (shown at 302). According to someembodiments, the read/write channel 226 of the storage device 208 mayprovide an independent signal-processing path for each of the readerelements 104A-104C. During a read operation by the storage device, eachof the reader elements 102A-102C provides a read signal through signalpre-processing elements 310 of the read/write channel 226 to themulti-reader decoder module 108. The pre-processing elements 310 mayinclude a variable-gain amplifier (“VGA”), an analog-digital converter(“ADC”), and the like.

In some embodiments, the signal from the reader element 102 may beprovided to a filter 312A-312C (referred to herein generally as filter312), such as a digital FIR filter that accounts for timing differencesin the signals from the associated reader elements 102A-102C thatresults from passing of the stored data by the readers at differenttimes as the disk 202 rotates underneath the read/write head 204. Thefilter may perform other processing of the read signals, such asmitigating noise in the signal. The filter 312 may also be referred toas an “equalizer.” The signal then passes to a multi-level detector314A-314C (referred to herein generally as multi-level detector 314)that detects multiple levels in the magnetic field on the recordingsurface under the associated reader (as opposed to the binary states ina traditional magnetic state detector). According to embodiments, thelevels associated with data stored on a single track in a non-return tozero (“NRZ”) digital magnetic recording scheme are {−1, +1}. The sign ofthe data may correspond to the direction of recorded mediamagnetization.

For each bit combination written on the three data tracks 104A-104C thatpass under the three reader elements 102A-102C, the multi-leveldetectors 314A-314C provide multi-level triplets to a mapper 316. Themapper 316 may then utilize an appropriate algorithm to detect the databits written to the target track, such as data track 104B, based on themulti-level triplets provided by the multi-level detectors 314A-314C.For example, TABLE 1 below provides an illustrative mapping between themulti-level triplets detected from the three reader elements 102A-102Cand the bit data contained on the three data tracks 104A-104C. The bitdata stored on each data track 104 will correspond to either −1 or +1,and the multi-level triplets can be seen to effectively represent asummation of the data over subsets of the three tracks, consistent withlinear superposition in the readback process. Utilizing the mappingsshown in TABLE 1, a simple algorithm to detect the bits in the targetdata track 104B (shown at b₂) may be implemented by the mapper 316 asfollows:

TABLE 1 Multi-level State Mappings (3 Reader) R1 R2 R3 b₁ b₂ b₃ 2 2 3 11 1 2 0 1 1 1 −1 0 0 1 1 −1 1 0 −2 −1 1 −1 −1 0 2 1 −1 1 1 0 0 −1 −1 1−1 −2 0 −1 −1 −1 1 −2 −2 −3 −1 −1 −1 b₂ = 1, if R1 = 2, or R2 = 2 b₂ =−1, if R1 = −2, or R2 = −2 b₂ = 1, if R1 = 0 and R2 = 0 and R3 = −1 b₂ =−1, if R1 = 0 and R2 = 0 and R3 = 1

The output from the mapper 316 may then be passed to a conventionalchannel decoder 318 to decode the user data from the target data track104. It will be appreciated that this example detection algorithmutilizing independent multi-level detectors 314 for each reader is onlyfor illustrative purposes and is not intended to represent an optimalsolution. Better detection algorithms or methods may be designed byjointly processing the three reader signals to yield the data for thetarget data track 104B. For example, the multi-reader decoder module 108may utilize a simple lookup in a mapping table stored in the memory 230or other storage area containing the mappings depicted in TABLE 1 toconvert the multi-level triplets to the data (b2) of the target datatrack 104B. It is intended that all such detection algorithms beincluded in this application. It will be further appreciated that in theexample system 300 shown in FIG. 3, there is no implicit mapping rateloss, and the storage device 200 can employ a conventional writeprocess, i.e., writing each track independently, thus not affecting thewrite performance of the device.

FIG. 4 shows aspects of another illustrative system 400 for utilizingmultiple, wide readers to read narrow data tracks on a magneticrecording media of a storage device. In order to reduce the number ofreader elements, hence the system cost, the read/write head 204 of thesystem 400 depicted in FIG. 4 incorporates only two reader elements 102Aand 102B. According to some embodiments, both of the reader elements102A and 102B are 2× the width of the written data tracks 104A-104C onthe storage media.

As in the system 300 shown in FIG. 3, the multi-level detectors 314detect multiple levels under each reader element 102A-102B and themulti-level detectors 314A-314B provide multi-level pairs to the mapper316. The mapper 316 then utilizes the appropriate algorithm to detectthe data bits written to the target track, such as data track 104B,based on the multi-level pairs provided by the multi-level detectors314. For example, TABLE 2 below provides an illustrative mapping tablemapping the multi-level pairs detected from the two reader elements 102Aand 102B to the bit data contained on the three data tracks 104A-104C.Utilizing the mappings shown in TABLE 2, a simple algorithm to detectthe bits in the target data track 104B (shown at b₂) may be implementedby the mapper 316 as follows:

TABLE 2 Multi-level State Mapping Table (2 Reader) R1 R2 b₁ b₂ b₃ 2 2 11 1 2 0 1 1 −1 >> 0 0 1 −1 1 0 −2 1 −1 −1 0 2 −1 1 1 >> 0 0 −1 1 −1 −2 0−1 −1 1 −2 −2 −1 −1 −1 b₂ = 1, if R1 = 2, or R2 = 2 b₂ = −1, if R1 = −2,or R2 = −2 b₂ = 1, if R1 = 0 and R2 = 0 and b₂ is on an even track b₂ =−1, if R1 = 0 and R2 = 0 and b₂ is on an odd track

However, because of the lack of the third reader, two different bitpatterns across the three data tracks 104A-104C maps to the same pair ofmulti-level values, specifically (0, 0), as shown in TABLE 2. This maycreate a problem for the detection algorithm utilized by the mapper 316.One approach to dealing with this problem is to eliminate one of thepatterns when writing data to the storage media that contributes to theredundant multi-level pair. In some embodiments, a two-dimensional(“2-D”) modulation-coding scheme may be implemented for this purpose,designed to eliminate the (1, −1, 1, −1, . . . ) pattern in thecross-track direction. However, since one of the eight patterns iseliminated, the best coding rate for such a 2-D modulation-coding schemewould be 7/8, which results in a loss in a 1/8 loss in overall storagecapacity. Also, in order to implement the 2-D modulation coding scheme,the controller 220 must know the patterns written at adjacent tracks,such as tracks 104A and 104B, when writing data to data track 104C,which may require additional buffers and other components to implementthe write process.

The use of the 2-D modulation-coding scheme may also affect writeperformance of the storage device 200. In order to make sure theperformance effect is minimized, the controller 220 may store theprevious two tracks of written information in a buffer and as the thirdtrack of data is being received and use the buffered data for datatracks 104A and 104B to jointly encode the data to be written to thethird data track 104C. Upon completing the write of the third data track104C, the controller 220 may then shift the tracks down in the buffer toallow for encoding of the next track.

FIG. 5 shows aspects of another illustrative system 500 for utilizingmultiple, wide readers to read narrow data tracks on a magneticrecording media of a storage device. The system 500 of FIG. 5 includesthree reader elements 102A-102C as in the example shown in FIG. 3.However, in this example the width of the written track (shown at 302)is closer to the width of the readers. For example, for a track width302 of substantially 25 nm, the width of reader element R1 102A may beapproximately 40 nm, while the widths of readers R2 102B and R3 102C maybe approximately 30 nm. The left edges of reader elements R2 102B and R3102C may be offset from the left edge of reader R1 102A by 0 nm and 10nm, respectively, while the right edges of reader elements R2 102B andR3 102C may be offset from the right edge of reader R1 102A by 10 nm and0 nm, respectively.

According to some embodiments, the read signals from the reader elements102A-102C may pass through the signal pre-processing elements 310 to themulti-reader decoder module 108. The signals may then be provided to amultiple-input single-output (“MISO”) filter 502, such as a finiteimpulse response (“FIR”) filter. The MISO filter 502 may account forphase differences in the signals from the associated reader elements102A-102C as well as mitigating noise in the signals. The MISO FIRfilter 502 may further be configured to combine the read signals fromthe reader elements 102A-102C to generate a synthesized readback signal.For example, a simple combining rule such asy_(SYNTH)=y_(R2)+y_(R3)−y_(R1) (where y_(RN) is the readback signal fromthe Nth reader) may be implemented to produce a synthesized readbacksignal y_(SYNTH) that approximates the signal generated from a narrowerreader R_(SYNTH), as shown at 504. The synthesized readback signaly_(SYNTH) would further have a better SNR than the signals from theindividual readers.

According to the reader dimensions above, for example, the width ofR_(SYNTH) 504 would be approximately 20 nm—appropriate for reading the25 nm data track 104. Adapting this scheme to a more general case wherethe three reader widths are W_(R1), W_(R2), and W_(R3), utilizing thesame combining rule above would result in a synthesized readback signaly_(SYNTH) that approximates the signal generated from a reader R_(SYNTH)of width W_(R2)+W_(R3)−W_(R1). The offsets for reader elements R2 102Band R3 102C may be derived from the difference in their respectiveread-widths to reader element R1 102A. The synthesized combined signaly_(SYNTH) may then be fed by the MISO filter 502 to a conventionalchannel decoder 318 in order to decode the user data from the targetdata track 104.

The system 500 shown in FIG. 5 relies on linear superposition in thereadback process. However, since MR heads are not perfectly linear andgenerally suffer from processing variations that lead to differences indimensions and signal characteristics (amplitude, readback noise, etc.),the MISO filter 502 and/or other components of the read/write channel226 may further be configured to compensate for the behavioraldifferences between the various reader elements 102 utilized in thesystem 500, so that signal combining may be performed as close tooptimal as possible.

The system 500 depicted in FIG. 5 also assumes that the three readerelements 102A-102C are reading the data track 104 in real-time (meaning,for example, that the three reader elements are located on a read/writehead 204 at a near-optimal position). The synthesized combined signaly_(SYNTH) would also be generated by the MISO filter 502 in real-time.FIG. 6 provides details of another system 600 for utilizing multiple,wide readers to read narrow data tracks that doesn't require thisreal-time restriction. The system 600 of FIG. 6 includes only two readerelements 102A and 102B located on the read/write head 204 with differentwidths. For examples, the two reader elements 102A and 102B may haveread widths of 40 nm and 30 nm respectively. The two reader elements102A and 102B may further be centrally aligned with each other in thecross-track direction.

The system 600 relies on multiple passes of the read/write head 204 overthe data on the data track 104 in order to perform the read. The threeread signals y_(R1), y_(R2), and y_(R3) from each reader element 102 areobtained in separate passes by positioning the appropriate reader of thetwo reader elements 102A and 102B in the appropriate position over thedata track 104 being read, as shown in FIG. 7. The read signals from thefirst two passes may be buffered in a buffer 602 implemented by themulti-reader decoder module 108 or another component of the controller220 and then combined with the read signal from the final pass using thesame combining rule described above to produce the synthesized readbacksignal y_(SYNTH) approximating reader R_(SYNTH) 504, as further shown inFIG. 7. In other embodiments, the buffer 602 may buffer intermediateapplications of the combiner rule to be combined with the subsequentread signal on the next pass.

As in the system 500 described above in regard to FIG. 5, thesynthesized combined signal y_(SYNTH) may then be fed by the MISO filter502 to the conventional channel decoder 318 in order to decode the datafrom the target data track 104 in conjunction with the last read pass.Because the system 600 relies on multiple passes to perform the read,the system 600 may be employed by the storage device 200 for performingread-retries when an initial, single-pass read operation of the datatrack 104 fails, according to some embodiments.

FIG. 8 illustrates one routine 800 for utilizing multiple, wide readersto read narrow data tracks on a magnetic recording media, according tosome embodiments. The routine 800 may be performed by storage devices200 implementing the systems 300 and 400 described above in regards toFIGS. 3 and 4. According to embodiments, the routine 800 may beperformed by the multi-reader decoder module 108 of a storage device 200during a read of a target data track 104B. In further embodiments, theroutine 800 may be performed by the controller 220 of the storage device200, by external processors or computing systems performing storageprocessing in the storage device, or some other combination of modules,processors and devices.

The routine 800 begins at step 802, where the multi-reader decodermodule 108 receives the read signals from multiple reader elements 102.For example, the multi-reader decoder module 108 may receive the readsignals y_(R1), y_(R2), and y_(R3) from the reader elements 102A, 102B,and 102C depicted in FIG. 3, respectively. The read signals may beprocessed through pre-processing components 310 of the read/writechannel 226 before being received by the multi-reader decoder module108, according to some embodiments.

From step 802, the routine 800 proceeds to step 804, where themulti-reader decoder module 108 performs multi-level detection on theread signals. According to some embodiments, the multi-reader decodermodule 108 may perform multi-level detection on each of the read signalsfrom the reader elements 102 independently, using separate multi-leveldetectors 314. In further embodiments, the multi-reader decoder module108 may process each of the read signals through an independentlyconfigured filter 312 in order to account for phase differences in thesignals from the associated reader elements 102 that results from thedata on the target data track 104B passing by the readers at differenttimes as the disk 202 rotates underneath the read/write head 204. Thefilters 312 may further mitigate noise in the signals.

From step 804, the routine 800 proceeds to step 806, where themulti-reader decoder module 108 decodes the data from the target datatrack 104B based on the multi-level detection of the read signalsperformed in step 804. For example, the multi-reader decoder module 108may utilize a mapper 316 to detect the bits in the target data track104B based on the multi-level triplets from the multi-level detectors314 utilizing any of the algorithms described above in regard to FIG. 3or 4. The detected bits may then be sent to conventional channeldecoder(s) 318 to decode the user data. From step 806, the routine 800ends.

FIG. 9 illustrates another routine 900 for utilizing multiple, widereaders to read narrow data tracks on a magnetic recording media,according to some embodiments. The routine 900 may be performed bystorage devices 200 implementing the systems 500 and 600 described abovein regards to FIGS. 5 and 6. According to embodiments, the routine 900may be performed by the multi-reader decoder module 108 of a storagedevice 200 during a read of a target data track 104. In furtherembodiments, the routine 900 may be performed by the controller 220 ofthe storage device 200, by external processors or computing systemsperforming storage processing in the storage device, or some othercombination of modules, processors and devices.

The routine 900 begins at step 902, where the multi-reader decodermodule 108 receives the read signals from multiple reader elements 102.For example, the multi-reader decoder module 108 may receive the readsignals y_(R1), y_(R2), and y_(R3) from the reader elements 102A, 102B,and 102C depicted in FIG. 5, respectively. The read signals may beprocessed through pre-processing components 310 of the read/writechannel 226 before being received by the multi-reader decoder module108, according to some embodiments. In further embodiments, the readsignals may be received over multiple passes of the read/write head 204over the data on the target data track 104. The read signals frompreceding passes may be buffered in a buffer 602 of the multi-readerdecoder module 108 to be utilized during the final pass.

From step 902, the routine 900 proceeds to step 904, where themulti-reader decoder module 108 filters the read signals to mitigatenoise in the signal and/or account for phase differences in the signalsfrom the associated reader elements 102 that results from the data onthe target data track 104 passing by the readers at different times asthe disk 202 rotates underneath the read/write head 204. The filteringmay be performed by the MISO FIR filter 502, according to someembodiments.

The routine 900 proceeds from step 904 to step 906, where themulti-reader decoder module 108 generates a synthesized readback signalby combining the filtered read signals from the multiple reader elements102. According to some embodiments, in the case of the systems 500 and600 with three read signals y_(R1), y_(R2), and y_(R3), a simplecombining rule such as y_(SYNTH)=y_(R2)+y_(R3)+y_(R1) may be utilized togenerate the synthesized readback signal y_(SYNTH) approximating thesignal generated from a narrower reader R_(SYNTH) 504. The combiningrule may be implemented in the MISO filter 502 or some other componentof the multi-reader decoder module 108. In some embodiments, one or moreof the signals y_(R1), y_(R2), and y_(R3) may be read by the MISO filter502 from the buffer 602 during the combining function.

From step 906, the routine 900 proceeds to step 908, where themulti-reader decoder module 108 decodes the data on the target datatrack 104 from the synthesized readback signal. For example, thesynthesized combined signal y_(SYNTH) may be fed to a conventionalchannel decoder 318 in order to decode the data from the target datatrack 104. From step 908, the routine 900 ends.

Based on the foregoing, it will be appreciated that technologies forutilizing multiple, wide readers to read narrow data tracks on amagnetic recording media are presented herein. It will be appreciatedthat the number, widths, alignment, and configuration of the readerelements 102 in the systems shown in the figures and described hereinare for illustrative purposes only. Systems may be implemented with two,three, or more reader elements 102 of varying widths or the same widthmay be utilized to read the narrow data tracks 104 of the storage device200 utilizing the methods and apparatuses described herein. In someembodiments, each of the reader elements 102 may have a width of aninteger multiple of the width of a data track 104 written to therecording media. In further embodiments, at least one reader element 102may be wider than the width of a data track 104. In still furtherembodiments, the reader elements 102 may be aligned on-centers on theread/write head 204.

Further, the read/write channel 226 of the controller 220 may containany number of read channels and components to support the multiplereader elements 102. It is intended that this application include allsuch combinations of reader counts, widths, and configurations and allsupporting channel configurations. While embodiments are describedherein in regard to an HDD device, it will also be appreciated that theembodiments described in this disclosure may be utilized to read data inany storage device containing data stored in substantially parallel orsubstantially concentric tracks on a magnetic recording media, includingbut not limited to, a magnetic disk drive, a hybrid magnetic and solidstate drive, a magnetic tape drive and the like. The above-describedembodiments are merely possible examples of implementations, merely setforth for a clear understanding of the principles of the presentdisclosure.

The logical operations, functions or steps described herein as part of amethod, process or routine may be implemented (1) as a sequence ofprocessor-implemented acts, software modules or portions of code runningon a controller or computing system and/or (2) as interconnected machinelogic circuits or circuit modules within the controller or computingsystem. The implementation is a matter of choice dependent on theperformance and other requirements of the system. Alternateimplementations are included in which operations, functions or steps maynot be included or executed at all, may be executed out of order fromthat shown or discussed, including substantially concurrently or inreverse order, depending on the functionality involved, as would beunderstood by those reasonably skilled in the art of the presentdisclosure.

It will be further appreciated that conditional language, such as, amongothers, “can,” “could,” “might,” or “may,” unless specifically statedotherwise, or otherwise understood within the context as used, isgenerally intended to convey that certain embodiments include, whileother embodiments do not include, certain features, elements and/orsteps. Thus, such conditional language is not generally intended toimply that features, elements and/or steps are in any way required forone or more particular embodiments or that one or more particularembodiments necessarily include logic for deciding, with or without userinput or prompting, whether these features, elements and/or steps areincluded or are to be performed in any particular embodiment.

Many variations and modifications may be made to the above-describedembodiments without departing substantially from the spirit andprinciples of the present disclosure. Further, the scope of the presentdisclosure is intended to cover any and all combinations andsub-combinations of all elements, features and aspects discussed above.All such modifications and variations are intended to be included hereinwithin the scope of the present disclosure, and all possible claims toindividual aspects or combinations of elements or steps are intended tobe supported by the present disclosure.

What is claimed is:
 1. A system for reading a data track on magneticrecording media, the system comprising: a read/write head comprising aplurality of reader elements configured to read a magnetic signal fromthe magnetic recording media, a width of each of the plurality of readerelements being an integer greater than 1 multiple of a width of the datatrack on the recording media; and a multi-reader decoder module operablyconnected to the read/write head and configured to receive a read signalfrom each of the plurality of reader elements, and decode the data onthe data track based on the read signals from the plurality of readerelements.
 2. The system of claim 1, wherein the read signals indicate asummation of data on the data track and one or more adjacent tracks. 3.The system of claim 1, wherein each of the plurality of reader elementshas a different alignment over the data track.
 4. The system of claim 1,wherein the multi-reader decoder module comprises: a plurality ofmulti-level detectors, each of the multi-level detectors configured todetect multiple levels in the read signals and generate an associatedmulti-level value; and a mapper configured to convert the multi-levelvalues from the plurality of multi-level detectors to bit data stored onthe data track.
 5. The system of claim 4, wherein the multi-readerdecoder module further comprises a plurality of filters configured toaccount for phase differences in the read signals from the plurality ofreader elements.
 6. The system of claim 1, wherein the multi-readerdecoder module comprises a multiple input single output (“MISO”) filterconfigured to combine the read signals from each of the plurality ofreader elements to generate a synthesized readback signal.
 7. The systemof claim 6, wherein the MISO filter is further configured to account forphase differences in the read signals from the plurality of readerelements.
 8. The system of claim 1, wherein the plurality of readerelements comprises three reader elements.
 9. The system of claim 1,wherein the plurality of reader elements comprises two reader elements,each of the two reader elements being substantially two times the widthof the data track.
 10. The system of claim 1, wherein the plurality ofreader elements are centrally-aligned with each other in a cross-trackdirection on the read/write head.
 11. The system of claim 1, wherein themulti-reader decoder module comprises a buffer configured to buffer theread signals from one or more of the plurality of reader elements andwherein reading the data on the data track require multiple passes ofthe data on the magnetic recording media beneath the read/write head.12. The system of claim 1, wherein the multi-reader decoder module iscontained in a controller configured to control a data storage device.13. A method for reading a target data track on a recording media, themethod comprising steps of: receiving a read signal from each of aplurality of reader elements, each of the read signals indicating asummation of data on the target data track and one or more adjacenttracks, the plurality of reader elements being centrally-aligned witheach other in a cross-track direction on a read/write head; anddetermining data on the target track based on the read signals from theplurality of reader elements.
 14. The method of claim 13, whereindetermining data on the target track based on the read signals from theplurality of reader comprises: determine a multi-level value for each ofthe read signals, the multi-level value indicating a level of a magneticfield on a surface of the recording media under the associated readerelement; and converting the multi-level values to bit data stored on thetarget data track.
 15. The method of claim 14, further comprisingpassing each of the read signals through a filter configured to accountfor phase differences in the read signals from the plurality of readerelements.
 16. The method of claim 13, wherein determining data on thetarget track based on the read signals from the plurality of readercomprises combining the read signals from each of the plurality ofreader elements to generate a synthesized readback signal indicating thedata in the target data track.
 17. The method of claim 13, furthercomprising buffering the read signals from one or more of the pluralityof reader elements and wherein reading the target data track requiresmultiple passes of the target data track on the recording media beneaththe read/write head.
 18. A read/write head of a hard-disk drive (“HDD”)device, the read/write head comprising three reader elements, two of thethree reader elements being substantially two times a width of a datatrack on a magnetic recording media of the HDD and the third of thethree reader elements being substantially three times the width of thedata track, wherein a controller of the HDD is configured to receive aread signal from each of the three reader elements and to determine dataon the data track based on the read signals from the three readerelements.
 19. The read/write head of claim 18, wherein each of the readsignals indicate a summation of data on the data track and one or moreadjacent tracks.
 20. The read/write head of claim 18, wherein thecontroller of the HDD is further configured to combine the read signalsfrom each of the three reader elements to generate a synthesizedreadback signal indicating the data in the data track.